11.
CAP Theorem› 2000: E. Brewer, N. Lynch› You can satisfy at most 2 out of the 3 requirements

12.
Consistency› The system is in a consistent state after an operation› All clients see the same data› Strong consistency (ACID) vs. eventual consistency (BASE) ACID: Atomicity, Consistency, Isolation and Durability BASE: Basically Available, Soft state, Eventually consistent

13.
Availability› System is “always on”, no downtime› Node failure tolerance – all clients can find some available replica› Software/hardware upgrade tolerance

14.
Partition tolerance› System continues to function even when split into disconnected subsets (network disruption)› Not only for reads, but writes as well

28.
“Map Reduce is the Uzi of aggregationtools. Everything described with count,distinct and group can be done withMapReduce, and more.”Kristina Chadorow, Michael Dirolf in MongoDB – The Definitive Guide